Category: rspec

RSpec – Test Doubles ”; Previous Next In this chapter, we will discuss RSpec Doubles, also known as RSpec Mocks. A Double is an object which can “stand in” for another object. You’re probably wondering what that means exactly and why you’d need one. Let’s say you are building an application for a school and you have a class representing a classroom of students and another class for students, that is you have a Classroom class and a Student class. You need to write the code for one of the classes first, so let’s say that, start with the Classroom class − class ClassRoom def initialize(students) @students = students end def list_student_names @students.map(&:name).join(”,”) end end This is a simple class, it has one method list_student_names, which returns a comma delimited string of student names. Now, we want to create tests for this class but how do we do that if we haven’t created the Student class yet? We need a test Double. Also, if we have a “dummy” class that behaves like a Student object then our ClassRoom tests will not depend on the Student class. We call this test isolation. If our ClassRoom tests don’t rely on any other classes, then when a test fails, we can know immediately that there is a bug in our ClassRoom class and not some other class. Keep in mind that, in the real world, you may be building a class that needs to interact with another class written by someone else. This is where RSpec Doubles (mocks) become useful. Our list_student_names method calls the name method on each Student object in its @students member variable. Therefore, we need a Double which implements a name method. Here is the code for ClassRoom along with an RSpec Example (test), yet notice that there is no Student class defined − class ClassRoom def initialize(students) @students = students end def list_student_names @students.map(&:name).join(”,”) end end describe ClassRoom do it ”the list_student_names method should work correctly” do student1 = double(”student”) student2 = double(”student”) allow(student1).to receive(:name) { ”John Smith”} allow(student2).to receive(:name) { ”Jill Smith”} cr = ClassRoom.new [student1,student2] expect(cr.list_student_names).to eq(”John Smith,Jill Smith”) end end When the above code is executed, it will produce the following output. The elapsed time may be slightly different on your computer − . Finished in 0.01 seconds (files took 0.11201 seconds to load) 1 example, 0 failures As you can see, using a test double allows you to test your code even when it relies on a class that is undefined or unavailable. Also, this means that when there is a test failure, you can tell right away that it’s because of an issue in your class and not a class written by someone else. Print Page Previous Next Advertisements ”;

RSpec – Basic Syntax ”; Previous Next Let’s take a closer look at the code of our HelloWorld example. First of all, in case it isn’t clear, we are testing the functionality of the HelloWorld class. This of course, is a very simple class that contains only one method say_hello(). Here is the RSpec code again − describe HelloWorld do context “When testing the HelloWorld class” do it “The say_hello method should return ”Hello World”” do hw = HelloWorld.new message = hw.say_hello expect(message).to eq “Hello World!” end end end The describe Keyword The word describe is an RSpec keyword. It is used to define an “Example Group”. You can think of an “Example Group” as a collection of tests. The describe keyword can take a class name and/or string argument. You also need to pass a block argument to describe, this will contain the individual tests, or as they are known in RSpec, the “Examples”. The block is just a Ruby block designated by the Ruby do/end keywords. The context Keyword The context keyword is similar to describe. It too can accept a class name and/or string argument. You should use a block with context as well. The idea of context is that it encloses tests of a certain type. For example, you can specify groups of Examples with different contexts like this − context “When passing bad parameters to the foobar() method” context “When passing valid parameters to the foobar() method” context “When testing corner cases with the foobar() method” The context keyword is not mandatory, but it helps to add more details about the examples that it contains. The it Keyword The word it is another RSpec keyword which is used to define an “Example”. An example is basically a test or a test case. Again, like describe and context, it accepts both class name and string arguments and should be used with a block argument, designated with do/end. In the case of it, it is customary to only pass a string and block argument. The string argument often uses the word “should” and is meant to describe what specific behavior should happen inside the it block. In other words, it describes that expected outcome is for the Example. Note the it block from our HelloWorld Example − it “The say_hello method should return ”Hello World”” do The string makes it clear what should happen when we call say hello on an instance of the HelloWorld class. This part of the RSpec philosophy, an Example is not just a test, it’s also a specification (a spec). In other words, an Example both documents and tests the expected behavior of your Ruby code. The expect Keyword The expect keyword is used to define an “Expectation” in RSpec. This is a verification step where we check, that a specific expected condition has been met. From our HelloWorld Example, we have − expect(message).to eql “Hello World!” The idea with expect statements is that they read like normal English. You can say this aloud as “Expect the variable message to equal the string ‘Hello World’”. The idea is that its descriptive and also easy to read, even for non-technical stakeholders such as project managers. The to keyword The to keyword is used as part of expect statements. Note that you can also use the not_to keyword to express the opposite, when you want the Expectation to be false. You can see that to is used with a dot, expect(message).to, because it actually just a regular Ruby method. In fact, all of the RSpec keywords are really just Ruby methods. The eql keyword The eql keyword is a special RSpec keyword called a Matcher. You use Matchers to specify what type of condition you are testing to be true (or false). In our HelloWorld expect statement, it is clear that eql means string equality. Note that, there are different types of equality operators in Ruby and consequently different corresponding Matchers in RSpec. We will explore the many different types of Matchers in a later section. Print Page Previous Next Advertisements ”;

RSpec – Writing Specs ”; Previous Next In this chapter, we will create a new Ruby class, save it in its own file and create a separate spec file to test this class. First, in our new class, it is called StringAnalyzer. It’s a simple class that, you guessed it, analyzes strings. Our class has only one method has_vowels? which as its names suggests, returns true if a string contains vowels and false if it doesn’t. Here’s the implementation for StringAnalyzer − class StringAnalyzer def has_vowels?(str) !!(str =~ /[aeio]+/i) end end If you followed the HelloWorld section, you created a folder called C:rspec_tutorialspec. Delete the hello_world.rb file if you have it and save the StringAnalyzer code above to a file called string_analyzer.rb in the C:rspec_tutorialspec folder. Here is the source for our spec file to test StringAnalyzer − require ”string_analyzer” describe StringAnalyzer do context “With valid input” do it “should detect when a string contains vowels” do sa = StringAnalyzer.new test_string = ”uuu” expect(sa.has_vowels? test_string).to be true end it “should detect when a string doesn”t contain vowels” do sa = StringAnalyzer.new test_string = ”bcdfg” expect(sa.has_vowels? test_string).to be false end end end Save this in the same spec directory, giving it the name string_analyzer_test.rb. In your cmd.exe window, cd to the C:rspec_tutorial folder and run this command: dir spec You should see the following − Directory of C:rspec_tutorialspec 09/13/2015 08:22 AM <DIR> . 09/13/2015 08:22 AM <DIR> .. 09/12/2015 11:44 PM 81 string_analyzer.rb 09/12/2015 11:46 PM 451 string_analyzer_test.rb Now we’re going to run our tests, run this command: rspec spec When you pass the name of a folder to rspec, it runs all of the spec files inside of the folder. You should see this result − No examples found. Finished in 0 seconds (files took 0.068 seconds to load) 0 examples, 0 failures The reason that this happened is that, by default, rspec only runs files whose names end in “_spec.rb”. Rename string_analyzer_test.rb to string_analyzer_spec.rb. You can do that easily by running this command − ren specstring_analyzer_test.rb string_analyzer_spec.rb Now, run rspec spec again, you should see output that looks like this − F. Failures: 1) StringAnalyzer With valid input should detect when a string contains vowels Failure/Error: expect(sa.has_vowels? test_string).to be true expected true got false # ./spec/string_analyzer_spec.rb:9:in `block (3 levels) in <top (required)>” Finished in 0.015 seconds (files took 0.12201 seconds to load) 2 examples, 1 failure Failed examples: rspec ./spec/string_analyzer_spec.rb:6 # StringAnalyzer With valid input should detect when a string contains vowels Do you see what just happened? Our spec failed because we have a bug in StringAnalyzer. The bug is simple to fix, open up string_analyzer.rb in a text editor and change this line: !!(str =~ /[aeio]+/i) to this: !!(str =~ /[aeiou]+/i) Now, save the changes you just made in string_analyizer.rb and run the rspec spec command again, you should now see output that looks like − .. Finished in 0.002 seconds (files took 0.11401 seconds to load) 2 examples, 0 failures Congratulations, the examples (tests) in your spec file are now passing. We fixed a bug in the regular expression which has vowels method but our tests are far from complete. It would make sense to add more examples that tests various types of input strings with the has vowels method. The following table shows some of the permutations that could be added in new Examples (it blocks) Input string Description Expected result with has_vowels? ‘aaa’, ‘eee’, ‘iii’, ‘o’ Only one vowel and no other letters. true ‘abcefg’ ‘At least one vowel and some consonants’ true ‘mnklp’ Only consonants. false ‘’ Empty string (no letters) false ‘abcde55345&??’ Vowels, consonants, numbers and punctuation characters. true ‘423432%%%^&’ Numbers and punctuation characters only. false ‘AEIOU’ Upper case vowels only. true ‘AeiOuuuA’ Upper case and lower vowels only. true ‘AbCdEfghI’ Upper and lower case vowels and consonants. true ‘BCDFG’ Upper case consonants only. false ‘ ‘ Whitespace characters only. false It is up to you to decide, which examples to add to your spec file. There are many conditions to test for, you need to determine what subset of conditions is most important and tests your code the best. The rspec command offers many different options, to see them all, type rspec -help. The following table lists the most popular options and describes what they do. Sr.No. Option/flag & Description 1 -I PATH Adds PATH to the load (require) path that rspec uses when looking for Ruby source files. 2 -r, –require PATH Adds a specific source file to be required in your spec. file(s). 3 –fail-fast With this option, rspec will stop running specs after the first Example fails. By default, rspec runs all specified spec files, no matter how many failures there are. 4 -f, –format FORMATTER This option allows you to specify different output formats. See the section on Formatters for more details about output formats. 5 -o, –out FILE This option directs rspec to write the test results to the output file FILE instead of to standard out. 6 -c, –color Enables color in rspec’s output. Successful Example results will display in green text, failures will print in red text. 7 -b, –backtrace Displays full error backtraces in rspec’s output. 8 -w, –warnings Displays Ruby warnings in rspec’s output. 9 -P, –pattern PATTERN Load and run spec files that match the pattern PATTERN. For example, if you pass -p “*.rb”, rspec will run all Ruby files, not just the ones that end in “_spec.rb”. 10 -e, –example STRING This option directs rspec to run all Examples that contain the text STRING in their descriptions. 11 -t, –tag TAG With this option, rspec will only run examples that contain the tag TAG. Note that TAG is specified as a Ruby symbol. See the section on RSpec Tags for more details. Print Page Previous Next Advertisements ”;

RSpec – Introduction ”; Previous Next RSpec is a unit test framework for the Ruby programming language. RSpec is different than traditional xUnit frameworks like JUnit because RSpec is a Behavior driven development tool. What this means is that, tests written in RSpec focus on the “behavior” of an application being tested. RSpec does not put emphasis on, how the application works but instead on how it behaves, in other words, what the application actually does. RSpec Environment First of all, you will need to install Ruby on your computer. However, if you haven’t already done earlier, then you can download and install Ruby from the main Ruby website − Ruby. If you are installing Ruby on Windows, you should have the Ruby installer for Windows here at − http://www.rubyinstaller.org For this tutorial, you will only need text editor, such as Notepad and a command line console. The examples here will use cmd.exe on Windows. To run cmd.exe, simply click on the Start menu and type “cmd.exe”, then hit the Return key. At the command prompt in your cmd.exe window, type the following command to see what version of Ruby you are using − ruby -v You should see the below output that looks similar to this − ruby 2.2.3p173 (2015-08-18 revision 51636) [x64-mingw32] The examples in this tutorial will use Ruby 2.2.3 but any version of Ruby higher than 2.0.0 will suffice. Next, we need to install the RSpec gem for your Ruby installation. A gem is a Ruby library which you can use in your own code. In order to install a gem, you need to use the gem command. Let’s install the Rspec gem now. Go back to your cmd.exe Window and type the following − gem install rspec You should have a list of dependent gems that were installed, these are gems that the rspec gem needs to function correctly. At the end of the output, you should see something that looks like this − Done installing documentation for diff-lcs, rspec-support, rspec-mocks, rspec-expectations, rspec-core, rspec after 22 seconds 6 gems installed Do not worry, if your output does not look exactly the same. Also, if you are using a Mac or Linux computer, you may need to either run gem install rspec command using sudo or use a tool like HomeBrew or RVM to install the rspec gem. Hello World To get started, let’s create a directory (folder) to store our RSpec files. In your cmd.exe window, type the following − cd Then type − mkdir rspec_tutorial And finally, type − cd rspec_tutorial From here, we’re going to create another directory named spec, do that by typing − mkdir spec We are going to store our RSpec files in this folder. RSpec files are known as “specs”. If this seems confusing to you, you can think of a spec file as a test file. RSpec uses the term “spec” which is a short form for “specification”. Since, RSpec is a BDD test tool, the goal is to focus on what the application does and whether or not it follows a specification. In behavior driven development, the specification is often described in terms of a “User Story”. RSpec is designed to make it clear whether the target code is behaving correctly, in other words following the specification. Let’s return to our Hello World code. Open a text editor and add the following code − class HelloWorld def say_hello “Hello World!” end end describe HelloWorld do context “When testing the HelloWorld class” do it “should say ”Hello World” when we call the say_hello method” do hw = HelloWorld.new message = hw.say_hello expect(message).to eq “Hello World!” end end end Next, save this to a file named hello_world_spec.rb in the spec folder that you created above. Now back in your cmd.exe window, run this command − rspec spec spechello_world_spec.rb When the command completes, you should see output that looks like this − Finished in 0.002 seconds (files took 0.11101 seconds to load) 1 example, 0 failures Congratulations, you just created and ran your first RSpec unit test! In the next section, we will continue to discuss the syntax of RSpec files. Print Page Previous Next Advertisements ”;

RSpec Tutorial PDF Version Quick Guide Resources Job Search Discussion RSpec is a unit test framework for the Ruby programming language. RSpec is different than traditional xUnit frameworks like JUnit because RSpec is a Behavior driven development tool. What this means is that, tests written in RSpec focus on the “behavior” of an application being tested. RSpec does not put emphasis on, how the application works but instead on how it behaves, in other words, what the application actually does. This tutorial will show you, how to use RSpec to test your code when building applications with Ruby. Audience This tutorial is for beginners who want to learn how to write better code in Ruby. After finishing this tutorial, you will be able to incorporate RSpec tests into your daily coding practices. Prerequisites In order to benefit from reading this tutorial, you should have some experience with programming, specifically with Ruby. Print Page Previous Next Advertisements ”;